Test

#include "mainwindow.h"
#include "./ui_mainwindow.h"
#include "raycaster.h"

#include <QThread>

class GenerateThread : public QThread {
public:
  GenerateThread(QSize viewportSize, qreal dpi)
      : m_viewportSize(std::move(viewportSize)), m_dpi(dpi) {
    qDebug() << QThread::currentThreadId();
  }

  void run() override {
    qDebug() << QThread::currentThreadId();

    RayCaster caster;
    m_result = caster.generate(QRectF(-0.5, -0.5, 1, 1), m_viewportSize, m_dpi);
  }

  QImage *result() { return &m_result; }

private:
  QSize m_viewportSize;
  qreal m_dpi;
  QImage m_result;
};

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent), ui(new Ui::MainWindow) {
  ui->setupUi(this);
}

MainWindow::~MainWindow() { delete ui; }

bool MainWindow::event(QEvent *event) {
  switch (event->type()) {
  case QEvent::Type::Resize: {
    ui->viewport->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
    qDebug() << "Resize to " << this->geometry().size();
    ui->viewport->resize(this->geometry().size());
    generateImage();
    break;
  }
  default:
    break;
  }
  return QMainWindow::event(event);
}

void MainWindow::generateImage() {
  auto *thread = new GenerateThread(ui->viewport->size(), devicePixelRatio());
  thread->start();
  // [5] Let the window know that the thread has finished
  QObject::connect(thread, &QThread::finished, this,
                   &MainWindow::threadFinished);
}

void MainWindow::threadFinished() {
  // [9] Receive the sender
  auto *generateThread = static_cast<GenerateThread *>(sender());

  if (generateThread->result()->size() !=
      ui->viewport->size() * devicePixelRatio())
    return;

  // [10] Instead of below:
  ui->viewport->setPixmap(QPixmap::fromImage(*generateThread->result()));

  // [6] Finally we set the image to the result
  ui->viewport->setPixmap(QPixmap::fromImage(*m_image));
}